There are kits in SG news that sell for around $425, give or take a few bucks. I purchased two of their kits about 4 years for $385.00 each. They come completely in parts. I had to assemble everything. Even the rear site was in a bag that had to be assemble. Some of the small parts bags had asian printing on them. The front hand guard was a tri-angle.
I just went and looked in my latest SG news and didn't see it in that one but I did see it recently. I believe Sarco has them. If you would like I can look at some of my older SG news.

I went back and looked into an older (Volume 62, Issue 35, Dec. 10, 2008) SG news. On page 63 Sarco has complete (minus receiver) AR-15 kits for $434.50. These kits have the GI handguards. All the small parts (Like the rear site) are in small bags and need to be put together. I think these kits would be great for putting together a "How to Build" CD.